Just had a quick look and your right, it appears that the screen load script has loaded and finished before the label is created, will have to go in plc, change the 2 to suit or just remove for the lbl to const update.
if testcount == 2 then
local cvMode = mc.mcProfileGetString(inst, 'CVFeedrate', 'CVMode', 'G64')
scr.SetProperty('lblCVMode', 'Label', cvMode)
end
DazTheGas